2
-20
Countermeasures Against Radio Interference
Radio noise is generated from the Drive as well as from the input and output lines. To reduce radio noise,
install noise filters on both input and output sides, and also install the Drive in a totally enclosed steel box.
The cable between the Drive and the motor should be as short as possible.
Fig 2.10 Countermeasures Against Radio Interference
Cable Length between Drive and Motor
Ground Wiring
Observe the following precautions when wiring the ground line.
•
Always use the ground terminal with a ground resistance of less than 10
.
•
Do not share the ground wire with other devices, such as welding machines or power tools.
•
Always use a ground wire that complies with technical standards on electrical equipment and minimize the
length of the ground wire.
Leakage current flows through the Drive. Therefore, if the distance between the ground electrode and the
ground terminal is too long, potential on the ground terminal of the Drive will become unstable.
•
When using more than one Drive, be careful not to loop the ground wire.
Fig 2.11 Ground Wiring
If the cable between the Drive and the motor is long, the high-frequency leakage current will increase, causing
the Drive output current to increase as well. This may affect peripheral devices. To prevent this, adjust the
carrier frequency (set in C6-01, C6-02) as shown in
. (For details, refer to
Chapter 3 User
Parameters
.)
Recommend setting Carrier frequency to 2 kHz to improve the life of the IGBTS. Can be
increased to reduce noise.
Table 2.6 Cable Length between Drive and Motor
Cable length
50 m max. (164 ft)
100 m max. (328 ft)
More than 100 m (> 328 ft)
Carrier frequency
15 kHz max.
10 kHz max.
5
kHz max.
IM
MCCB
Power
supply
Drive
Noise
filter
Metal pipe
Noise
filter
Steel box
OK
NO
